Magnetic structure



Nov. 19, 1940.

MAGNETI C STRUCTURE Filed Aug. 20, I958 H. G. QNEHE 2.222425 2 Sheets-Sheet 1 0 IO 20 so 40 so 'TEMPERA TURE. "c

CIRCUIT FIG. 4

200 400 50p TEMPERATURE c r //v VENTOR y H. 6. WE HE A TTORNEV MAGNETIC STRUCTURE Filed Aug. 20, 1938 2 Sheets-Sheet 2 lNl EN TOR H. 6. WE HE ATTORNEY Patented Nov. 19, 1940 MAGNETIC STRU f Herman G. Wehe, New York, N. Y. assignor to Bell Telephone laboratories, Incorporated, New

York, N. E, a corporation of New York Application August 20, 1938, Serial No. 225,913

' -13 Claims.

This invention relates to magnetic structures for converting radiant energy by magnetic means into other forms of energy and particularly to relays which are controlled by radiant energy.

One object of the invention is to provide a magnetic structure that shall be controlled-in an improved manner by received radiant energy. Another object of the inventionis to provide a magnetic structure that shall have the permeability of a magnetic circuit controlled in accordance with received radiant energy.

Another object of the invention is to provide a magnetic structure having a magnetic circuit completed with a material having a Curie region much lower than the Curie region of iron that shall be'controlled in an improved manner by radiant energy.

A further object of the invention is to provide a relay having two magnetic circuits including pyromagnetic material differently aifected in the two magnetic circuits by radiant energy impressed thereon to indicate received signals in the form of radiant energy.

When magnetic materials are subjected to heat, a change takes place in the permeabilities 'of the materials. A temperature permeability curve for a magnetic material shows that the material suddenly loses its magnetic properties when heated to a predetermined temperature. 80 The temperature permeability curve for a magnetic material has very steep portions in the region where the material ceases to be magnetic. The term Curie region is intended to cover that portion of a temperature permeability curve where a small change in temperature causes a large change in permeability. The Curie regions for different materials are in many cases widely separated. The Curie region for iron is high and a very high temperature is necessary 'to 40 cause iron to lose its magnetic property. Certain alloys have been found to have relatively low Curie regions when compared with the Curie region of iron. Material composed of per cent nickel and '70 per cent iron has been found to 5 have a relatively low Curie region.

According to the invention it has been found that the permeability of certain magnetic materials, for example the above-mentioned material composed of 30 per cent nickel and 70 50 per cent iron, may be readily changed by radiant energy if the surface of the magnetic material is darkened. 'The surface of the magnetic material may be darkened by applying a coating of lampblack or graphite combined with a binder material.

In one form of the invention a core composed of suitable laminations of iron is constructed with I a base portion and'three projecting legs. An energizing coil connected to a suitable source of alternating current is mounted on the central 5 leg. Two output windings respectively mounted on the two outside legs are oppositely connected to an output circuit. The output circuit is connected to a suitable receiver, such as car phones, and may, if so desired, be provided with an am- 10 pliiier. A strip of pyromagnetic material is mounted on the free ends of the three core legs. The pyromagnetic material should have a very low Curie region as compared with the Curie region of iron. This material may be composed 16 of 30 per cent nickel and '70 per cent iron, if so desired. A portion of the surface of the pyromagnetic strip is darkened in any suitable manner. as by applying arcoating of lampblack or graphite combined with a suitable binder mago terial. The portion of the pyromagnetic strip having the darkened surface formed thereon is included in one magnetic circuit of the magnetic structure whereas the other part of the strip free from the coating of darkened ma- 25 terial is included in the other magnetic circuit of the magnetic structure.

In a magnetic structure constructed as above set forth, no currents will flow through the output circuit under normal conditions because the so two output windings have equal and opposite currents generated therein. Thus no signals will be heard in the ear phones. However, if a radiant energy signal is applied to the pyromagnetic strip, the permeability of the different sec.- 35 tions of the strip will vary diflerently so that one of the output windings will have a stronger current generated in it than is generated in the other output winding. The radiant energy applied to the strip may be produced by an in- 40 condescanet or other suitable lamp. Radiant heat may also be impressed on the pyromagnetlc strip. When radiant energy is applied to the strip, the darkened surface absorbs a quantity of the energy which is turned into heat for changing the permeability of that portion of the pyromagnetic strip associated therewith. The portion of the pyromagnetic strip having no darkened surface thereon will not absorb nearly so much of the radiant energy.

In the above manner radiant energy signals may be employed for producing signals in the ear phones attached to the output circuit of the magnetic structure. Preferably the energizing winding on the central leg of the core is energized" by alternating current but if so desired, this winding may be energized by direct current.

In the accompanying drawings:

Fig. 1 is a diagrammatic view of a relay magnetic structure constructed in accordance with the invention;

Fig. 2 is a diagrammatic view of a modification of the relay structure shown in Fig. 1;

Fig. 3 is a permeability temperature curve of a pyromagnetic material composed oi 30 per cent nickel and 70 per cent iron;

Fig. 4 is a permeability temperature curve of iron;

Fig. 5 is a modification 'of the magnetic structure shown in Fig. 1 wherein an oscillation circuit is controlled in accordance with radiant energy signals;

Figs. 6 and '7 are diagrammatic views of modified relay magnetic structures which employ a single winding.

Referring to Fig. l of the drawings, a magnetic structure I comprises a core 2 having a base portion 3.,and three projecting legs 4, 5, and 8. An energizing winding I is mounted on the central leg 5 and two output windings 8 and 9 are respectively mounted on the outside legs 4 and 6. The energizing winding I is connected to a suitable source of alternating current I0. However, if so desired the winding 1 may be ener-' gized by a suitable battery II as shown in Fig. 2 of the drawings. The output windings 8 and 9 are oppositely connected to an output circuit I2. Thus, when the windings 8 and 9 are subjected to like magnetic forces, the output from the circuit I2 will be zero. The output winding I2 is connected to a suitable indicator, for example, a set of car phones I3. If so desired a suitable amplifier I4 may be provided in the circuit I2.

A pyromagnetic strip I5 is positioned across the core legs 4, 5 and 8 so as to complete two magnetic circuits through the core 3. The strip I5 is composed of a material having a low Curie region as compared with the Curie region of iron. For example, the strip I5 may be composed of 30 per cent nickel and '70 per cent iron. The permeability temperature curve for a material composed of 30 per cent nickel and '70 per cent iron is shown in Fig. 3 of the drawings. It will be noted that when this material is subjected to a temperature of the order of 20 C. the permeability of the material rises to a maximum and drops rapidly. The curve shown in Fig. 3 of the drawings has portions A and B which are very steeply inclined and called the Curie region. The magnetic structure I may, if so desired, be operated on either steeply inclined portions A and B of the curve shown in Fig. 3. If the magnetic structure is operated on the portion A of the curve shown in Fig. 3, an increase in heat will cause an increase in the permeability. If the magnetic structure is operated on the portion B of the curve shown in Fig. 3 an increase in heat will cause a decrease in the permeability of the magnetic circuit. Preferably the magnetic structure is operated on the portion 3' of the curve shown in Fig. 3 01. the drawings.

The strip I5 has a darkened coating II formed on-a portion I6 thereof. The darkened coating I! may be composed of lampblank or graphite with a suitable binder material. The portion I6 of the strip I5 having the darkened surface II thereon completes a magnetic circuit which includes the legs 5 and 6 of the core 3. A portion l8 of the strip I5, which has no darkened surface formed thereon, completes a magnetic circuit including the legs 4 and 5 of the core 3.

An incandescent lamp I8 connected to a source 28 by means of a switch 2| is provided for impressing radiant energy signals in the form of light on the strip I5. If the switch 2I is closed, and the lamp I8 lighted, radiant energy in the form of light will be directed across both portions I6 and I8 of the strip I5. The darkened surface I'I formed on the portion I8 of the strip will absorb a greater portion of the energy and will heat the portion, I6 of the strip to lower the permeability of the portion I6. In this apparatus it is assumed the strip I5 is operated on the portion B of the curve shown in Fig. 3. Thus the permeability of the magnetic circuit including the core legs 5 and 6 will be much less than the permeability of the magnetic circuit including the core legs 4 and 5. Accordingly, more energy will be induced in the output winding 8 than will be induced in the output winding 8. Consequently, a signal will be produced in the ear phones I3.

A tone will be. heard in the ear phones I3 if the energizing winding I is connected to an alternating current source. If the energizing winding 1 is connected to a direct current source, then only one pulse of current will be induced in the output winding 8 for giving one signal in the ear phones I3. It is, of course, apparent thatradiated heat from any suitable source may also be employed to operate the magnetic structure.

Referring to Fig. 2 of the drawings, a modification of the magnetic structure shown in Fig. l is illustrated which may also serve as a temperature indicator. Like parts of the apparatus shown in Fig. 2 to those shown in Fig. 1 will be indicated by similar reference characters. The'output circuit and the means shown for producing radiant energy, in Fig. l, have been omitted from the apparatus shown in Fig. 2.

A strip of pyromagnetic material 23 having a low Curie region as compared with iron is connected across the two'legs 5 and-8 of the core .3. The strip 23 may be formed of a material comprising 30 per cent nickel and '70 per cent iron.

A darkened surface 24 is formed on the strip 23 to increase the heating effect when the strip is subjected to radiant energy waves. The darkened surface 24 formed on the strip 23 may be composed of lampblack or graphite with a suitable binder material.

A second strip 25 is connected across the two legs 4 and 5 of the core 3. The strip 25 may be formed of iron or any other material havin a relatively high Curie region. In the operationof the structure shown in Fig. 2, the strip 25 must only have a Curie region difl'erent from the Curie region of the strip 23. The strips 23 and 25 are formed of such size that under normal temperature conditions the magnetic cir cuits of the output windings 8 and 8 produce equal and opposite potentials in the output circuit. However, if heat is applied to the strips 23 and 25 or if radiant energy is applied to the strips 23 and 25, the permeability of the magnetic strip, including the strip- 23, will be reduced as compared to the permeability of the magnetic circuit including the strip 25. Accordingly, a signal will be produced in the output circuit for operating the ear phones.

The permeability temperature curve of iron shown in Fig. 4 of the drawing indicates the de- 7 gree of heat required to effect any substantial decrease in the permeability of iron. Fig: 3-sh0ws the permeability temperature curve for a strip composed of 30 per cent nickel and 70 per cent iron as above set forth. The energizing winding 1 in the magnetic structure shown in Fig. 2 may be energized either from an alternating current source as shown in Fig. '1 or by a direct current source as shown in Fig. 2.

Referring to Fig. 5 of the drawings, a pyromagnetic relay is shown which may be operated by means of radiant energy signals. The relay comprises a ring 26 of magnetic material having a relatively low Curie region as compared to the Curie region of iron. Preferably. the ring 26 is composed of 30 per cent nickel and '70 per cent iron. A darkened coating 27 is formed on the outside surface of the ring 28. This coating may be composed of lampblack or graphite combined with a suitable binder material. The ring 26 is supported by suitable spokes 28 on a rotatable shaft 29. The shaft 29 also carries an adjustable plate 30 of a condenser 3|. The adjustable condenser plate 80 cooperates with stationary plates 32 and 33. The condenser 31 is connected to a suitable oscillatory circuit 34 so that signals may be indicated by the change in tuning of the cirsuit 36. A permanent magnet 35 in the shape of a horseshoe is provided for subjecting the ring 26 to magnetic lines of force. A stationary pin 36 is provided for engaging one of the spokes 28 to limit the movement of the ring 21 in a counter-clockwise direction. A suitable spring 31 is provided to return the ring 26 to initial position.

A light 89 which may be connected by a switch to to a suitable source ti is provided for controlling the rotative movement of the ring 26. The lamp 39 is positioned to impress radiant energy at a point d2 on the ring 26 adjacent to one side of the permanent magnet 35. radiant energy is applied at the point 12 of the ring 28, the magnetic pull of the permanent mag-" net of that portion of the ring 26 will be weakened because of the reduction in the permeability of that portion of the ring. Consequently. the ring 26 will be given a rotative movement in a clockwise direction. The rotative movement of the ring 26 changes the setting of the condenser 3! to adjust the oscillatory circuit 34. If a light signal were applied to a point Q3 on the ring .26, and the ring was free to move, it would be given a movement in a counter-clockwise direction. It

is also apparent that if the ring 26 were free to rotate that continuous application of light to the point 42 or the point 43 would cause rotation of the ring in a clockwise direction or in a counterclockwise direction. The darkened surface 21 on the ring 26 absorbs the radiant energy converting it to heat so that it will be effective in changing the magnetic properties of the ring 28.

Referring to Fig. 6 of the drawings a magnetic structure is ilustrated having a core i0 comprising a base'section ii and two legs 72 and 18' projec ing therefrom. A strip 14 of pyromagnetic mat rial is connected across the legs 73 and 12. The strip 14 is preferably composed of 30 per cent nickel and '70 per cent iron. A blackened coating 75 is formed on the surface of the strip 74. This blackened coating may be composed of lampblack or graphite with a suitable binder materiaL- A winding 16 which is mounted on the base portion H of the core is connected through a battery 11 to a suitable-galvanometer 18. A lamp l9 is'con- :nected to battery 80 by a switch BI and serves to When impress radiant energy signals on the surface ll of the strip 14. I

Upon operation of the switch 8! radiant energy in the form of light is impressed on the strip II. The light waves absorbed by the surface I! are changed into heat to lower the permeability of the strip 14. This lowers thecurrent flow through the winding I6 to give an indication by the galvanometer 18 of the received signal.

In Fig. '7 of the drawings a modification of the structure shown in Fig. 6 is illustrated comprising a permanent horseshoe magnet 82 having a winding 83 thereon. The winding 83 is connected to a suitable galvanometer 84. A strip 85 of pyromagnetic material is connected across the ends of the horseshoe magnet 82. The strip 85 is composed of a material having a low Curie region. The strip may be composed of 30 per cent nickel and 70 per cent iron. A lamp 88 connected to a battery 81 by a switch 88 is provided for impressing radiant energy signals on the strip 85. A blackened coating 89 is formed on the strip 85 to absorb the received radiant energy waves and change them into the form of heat. The blackened coating may be composed of lampblack or graphite combined with a suitable binding material. The structure shown in Fig. 7 operates in glare ssame manner as the structure disclosed in Modifications in the apparatus and in the arrangement and location of parts may be made within the spirit and scope of the invention and such modifications are intended to be covered by the appended claims.

material for indicating-when the. material is subjected to radiant energy.

2. In combination, pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof, means for subjecting said pyromagnetic material to a magnetic field; means for subjecting said pyromagnetic material to radiant energy in a manner to change the per-. meability thereof, indicating means and means controlled upon change in the permeability-of said pyromagnetic material to operative said indicating means.

3. In combination, pyromagnetic material operating at a temperature in the Curie heat sensitive region, means for producing a magnetic field to include said pyromagnetic material, a surfaceof dark material formed on said pyromagnetic material for absorbing radiant energy waves to heat the pyromagnetic material, means for subjecting said pyromagnetic material to radiant energy, and means controlled by the change in the permeability of said pyromagnetic material for insubjected to radiant energy, means for impressing a magnetic field on said pyromagnetic material, means for subjecting said pyromagnetic material to radiant energy and means controlled by the change in the permeability of said pyromagnetic material for indicating when the material is subjected to radiant energy.

5. In combination, pyromagnetic material composed of 30 per cent nickel and '10 per cent iron and having a Curie region close to normal room temperatures, means for subjecting said pyro-- magnetic material to a magnetic field, means at times for subjecting said pyromagnetic material to radiant energy in a manner to change the permeability thereof, indicating means and means operated upon change in the permeability of said pyromagnetic material by radiant energy for controlling said indicating means.

6. In combination, a core having three polepieces projecting from a straight section, a wind ing mounted on each of said pole-pieces, a source of current connected to the winding mounted on the central pole-piece, an output circuit connected in series to the windings mounted on the two outside pole-pieces, said windings on the two outside pole-pieces being connected to have opposite effects on the output circuit, pyromagnetic material operating in the Curie heat sensitive region thereof and connected across the free ends of said pole-pieces to complete two magnetic circuits having the same permeabilities under normal conditions and means for insuring different permeabilities by the pyromagnetic material in the two magnetic circuits when the pyromagnetic material is subjected to radiant energy so that the two outside windings supply no current to the output circuit when the magnetic circuits have the same permeabilities and supply current to the output circuit when the permeabilities of the two magnetic circuits are different.

'7. In combination, a core having three projecting pole-pieces, means comprising pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof for completing two magnetic circuits through said core, means for varying differently the permeability of the pyromagnetic material in the two magnetic circuits when subjected to radiant energy, a winding connected to a source of current for enersizing said two magnetic circuits, two equal output windings respectively controlled by said two magnetic circuits and means comprising an output circuit oppositely connected to said output windings for indicating when the permeabilities of said magnetic circuits vary difierently.

8. In combination, a core, an energizing winding and two output windings mounted on said core, a source of current connected to said energizing winding, means comprising pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof for completing two magnetic circuits through said core, means for varying the permeability of the pyromagnetic material in the two circuits differently when subjected to radiant energy, said magnetic circuits respectively linking the two output windings, and means comprising an output circuit oppositely connected to said output windings for indicating when the permeability of said magnetic circuits are varied difierently by subjecting said pyromagnetic material to radiant energy.

9. In combination, acore of magnetic material having three pole-pieces projecting from a straight section, a winding mounted on each of said pole-pieces, a source of current connected to the winding mounted on the central pole-piece, an output circuit connected in series with the windings mounted on the two outside pole-pieces, said windings on the two outside pole-pieces being connected to oppose each other in the output circuit, and two strips of magnetic material respectively connecting the free ends of the outside pole-pieces to the free end of the central pole-piece, the two strips being operated at a temperature in the Curie heat sensitive region thereof, and means for insuring changing of the permeabilities of the two strips diflerently when subjected to radiant energy so that current flows in the output circuit.

10. In combination, a relay comprising a threelegged core having a strip of pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof and connected across one end of the core legs, a winding mounted on each of said legs, two of said windings being connected in series to an output circuit so as to have opposite effects on the output circuit, a source of current being connected to the third winding, and a darkened surface formed on said strip of pyromagnetic material between two of said legs for varying the heating of the strip when subjected to radiant energy to induce currents of different amounts in the two windings connected to the output circuit.

11. In combination, a core member, an energizing winding and two output windings mounted on said core, means comprising pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof for completing two magnetic circuits through said core, a darkened surface formed on a portion of said pyromagnetic material to vary the permeabilities of the two magnetic circuits when the pyromagnetic material is subjected to radiant energy, a source of current connected to said energizing winding for energizing said magnetic circuits, said two output windings being respectively linked with said two magnetic circuits, and means comprising an output circuit oppositely connected to said output windings for indicating when the permeability of said magnetic circuits are varied differently by subjecting said pyromagnetic material to radiant energy.

12. In combination, pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof, means for producing a magnetic field to include said pyromagnetic material an energy absorbing surface formed on said pyromagnetic material for absorbing radiant energy waves to heat the pyromagnetic material, means for subjecting said pyromagnetic material to radiant energy and means controlled by the change in the permeability of said pyromagnetic material for indicating when the material is subjected to radiant energy.

13. In combination, pyromagnetic material operating at a temperature in the Curie heat sensitive region thereof, means for subjecting said pyromagnetic material to a magnetic field, a

source or radiant energy applied to said pyromagnetic material, means for controlling the application of said radiant energy to said pyromagnetic material so that different parts of said material receive different amounts of the radiant energy and indicating means controlled according to the change in permeability of said pyromagnetic material.

HERMAN G. WEI-IE. 

